Gelled jet fuel



United States Patent 3,507,635 GELLED JET FUEL Amir M. Sarem, Yorba Linda, Calif., assignor to Union Oil Company of California, Los Angeles, Calif., a corshear conditions, it liquifies due to degradation of the molecule and is suitable for pumping to the jet engine.

Commercial jet fuels contemplated by the invention include JP1, JP3, JP4, JP5, let A, Jet A1, etc. and surprisingly, it has been found that polyisobutylene is com- 5 ggg gf g 13523 31 24, 1967 655,295 patable with these et fuels and forms a homogeneous gel Int. C1. 0101 7/00 therewith. mg C 44 7 6 Cl i Suitable polyisobutylenes range in molecular weight from about 80,000 to 250,000 and higher. If the molecular 10 weight is decreased below about 80,000 gel formation ABSTRACT OF THE DISCLOSURE can only be attained at the expense of an undesirably high 11 d t f 1 0d b 1 Oh i lene concentration of polyisobutylene. If the molecular weight g zfi g igfi g g ,1335; 22 g ha is increased beyond about 250,000 the concentration of pumped to a jet engine as a fluid the polyisobutylene is decreased to about 1% or less.

' 15 Generally the concentration range of polyisobutylene which may be suitably employed varies from about 1% This invention relates to jet fuel compositions and to about The lower concentiation of polylsobutylene more specifically to a jet fuel which has been gelled by requlres hlgber mleculaf Welght to i the blending with polyisobutylene. essary propert es of gellation and pumpabili ty. As the Jet fuel used in aircraft is potentially hazardous fol- Cnc.entratwn 15 Increased the molecular .Welght lowing a plane crash because it usually escapes from its polylsokiutylene must be decreased to retain the desired ruptured container tank, spreads and burns. It is quite Propertles' h b possible that in most crashes involving jet planes, many The mgxlmum i ecgve vllsgoslty W N may e emlives could be saved if the fuel remained in its tank, ployedw pump 9 t fue 1S abou'dt even if the tank was rupturei The minimum viscosity of the fu el 1n the gel state Jet fuel contained in large storage tanks at an airport i p h fuel 18 to remam Subalso presents a similar potential fire hazard although on stanna y In Its continue? 0] owmg f p a lesser scale. Should a tank fire develop or if the jet Consequently any sintable com.bm'atlon of i fuel were to leak out and burn, a dangerous situation Welght Concentratlon of polylsobutylene whlch i could develop Not only would property and lives b3 cause the et fuel to gel at about 5000 cps. or greater in endangered but airport operations could be interrupted storage q about 800 or 168.3 t Bumped and this too is undesirable to the et engine is contemplated by this invention.

Attempts have been made to gel jet fuel but problems slipenniposed .over ihese factors as the temPerature then arise when attempting to pump the fuel at a conc9nslderatlon Whlch W111 Vin-y the gel E trolled flow rate; in addition, combustion must be smooth vlously a fuel may be Suitable gel 0 but y and even, with a minimum of residue formation. Connot Possess thesfa propmes 1f the ambient temperature sequently no commercially acceptable gelled jet fuels are 100 accordmgly. i i operamigl temperature W111 available which combine the properties of satisfactory vilryt Si prgpertles m tum.wll alter the melee gellation, controlled pumpability, and low residue forma- 40 l at i t 2. goncentranon requlremeius of the 9 tion while still maintaining the necessary power output on lsobuty fine W 16 prodouce these propemes i l p combustion temperature (about 75 F.), a 5% concentration in Jet With the above drawbacks in mind it is an object of fuel 0f Polylwbutylene havmg a molecular Weght of this invention to provide a gelled jet fuel composition. about has been found to Produce the best gel Another object is to provide a jet fuel which has been propgtles' gelled by adding polyisobutylene' 7 Suitable commercial grades of polyisobutylene may be Another object is to provide a gelled jet fuel which obtamed from the Eniay Chemical Company under i can be pumped at suitable speeds and constant rates. trademark m of vlstainex Smtable grades are deslg Another object is to provide a gelled jet fuel-polyisoi g j gfiz 1 55% ig a s ig 1400; MM butylene composition which tends to remain in its conan T Hlg er molecular tamer even after the container is ruptured. wleight grades (i.e. exceeding 250,000) may be employed Another object is to provide a gelled jet fuel-polyisoa butylene composition which maintains satisfactory turbine Table I mus.trates h gel propertles of vanous engine fu e1 requirements when in a 1i quifi e d 8mm fuels blended with poly sobutylene. The shear degradation Another object is to provide a gelled jet fuel-polyiso produced by Waring Blendorfm "i polylsobinylfane' butylene composition which yields a low residue upon et fuel blend for 15 minutes. The viscosity determinations burning were made at two different shear rates.

TABLE. I

Polyisobutylene Bi-ookfield viscosity, cps. F. and shear rate, sec.

Cone, 0.12 12 Sample Mu]. wt. percent Tet iuel Fresh Degraded Fresh Degraded 1 140. 000 i JP4 170 9 7 2. 10.000 5 JP5 170 105 o 9 3 so, 000 3 W5 5, 000 800 3, 500 600 4 140, 000 5 JP4 10, 000 330 4, 900 250 5 140, 000 5 JP5 9, 000 400 5, 200

These and other objects will become apparent from the It will be observed from Table I that the gelled fuel description to follow. can be readily thinned by degradative high shear action, The objects of the invention are attained by incorporat- 70 and in this low viscous state, may be pumped to the jet ing polyisobutylene into jet fuels thereby obtaining a gelled composition; when the gel is placed under high engine readily.

It will be observed also that Samples 1 and 2 do not form a useful gel; Sample 3 represents the limits of acceptability because of low gel formation and high viscosity after undergoing shearing; Sample 4 and 5 are acceptable both with regard to gel formation and with regard to pumpability.

In actual practice, weighed amounts of polyisobutylene are added to the jet fuel in the fuel tank and the mixture is gelled by agitation for a suitable length of time. Prior to pumping to the jet engine, the gelled fuel is subjected to high shear degradative action by lowering a mixing device into the gel and converting it to a low viscous fluid which is then pumped to the engine. Preferably the mixer is adapted for travelling so when one portion of the gel is fluidized, the mixer is moved to another portion of nonfluidized gel in the fuel container.

Another advantage of this process is that the fuel becomes hot due to the high shear degradation; consequently the present process enables hot fuel to be pumped to the jet engine and this improves combustion efiiciency.

In storage situations, e.g., at an airport, the jet fuel may be stored by itself in container tanks and the polyisobutylene can be added to the fuel when conditions warrant, e.g., overheating, threat of fire, leakage, etc. If desired, the polyisobutylene can be added in amounts only necessary to produce a thin gel. Such a low viscosity gel will be easier to pump and otherwise handle than a gel having the high viscosity properties required for use in a jet aircraft.

If desired, a polar solvent swelling agent such as acetone may be employed with the polyisobutylene to expedite dissolving in the jet fuel. Also, the polyisobutylene may be comminuted by powdering, dicing, etc. to decrease the time required for dissolving.

I claim:

1. A gelled jet fuel composition containing about 5% 4 by weight of polyisobutylene having a molecular weight of about 140,000.

2. A gelled jet fuel composition containing about 1% of polyisobutylene having a molecular weight beyond about 250,000.

3. A gelled jet fuel composition containing about 5-8% polyisobutylene having a molecular weight between about 80,000140,000 and about -92% by weight of a jet fuel.

-4. A gelled jet fuel composition containing about 58% polyisobutylene having a molecular weight between about 80,000-140,000 and about 95-92% by weight jet fuel, the concentration and molecular Weight of polyisobutylene being selected to provide a Brookfield Viscosity (0.12

shear rate) of 5,00010,000 for undegraded polyisobutyl- References Cited UNITED STATES PATENTS 2,927,849 3/1960 Greblick et a1. 44-62 DANIEL E. WYMAN, Primary Examiner C. F. DEES, Assistant Examiner UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 .507 .635 Dated April 21 1970 Inventor(s) Amir M Sarem It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 4, line 21:

"Viscosity of" should read Viscosity (12 shear rate) of Signed and sealed this 22nd day of December 1970.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. WILLIAM E. SCHUYLER, JR. Attesting Officer Commissioner of Patents F ORM PC4050 (10-69] USCOMM-DC 60376-P69 t UJ. eovnmuur "mime ornc: nu o-au-su 

